Overview

The Harrison Spectral Gate is a unique gate plugin that can learn and differentiate between the spectral characteristics of the desired “Source” material and the undesired “Spill” within a signal for easier and more accurate triggering.

Supported formats:

• AAX
• VST
• VST3
• AU

Supported channel configurations:

• Mono
• Stereo

Latency: 2048 samples

 

Controls/Components

Learn Source

Learns the desired “Source” material within the signal being played. The Source is any part of a signal that you want to pass through the gate unaffected. While the Learn Source button is engaged, any input signal that is played will be recognized as the Source signal and the green Source line on the Spectrum Display will adhere to the shape of the input spectrum to capture the frequencies present in the Source material.

Click this button only when the desired part of the signal is being played to learn the Source signal. If necessary, the button can be held after clicking to include any tail that the Source signal might have. Just make sure the button is released before any undesired spill is played, otherwise it will be picked up as part of the Source signal.

 

Learn Spill

Learns the undesired “Spill” material within the signal being played. The Spill is any part of a signal that you want to be attenuated or “gated-out”. While the Learn Spill button is engaged, any input signal that is played will be recognized as the Spill signal and the red Spill line on the Spectrum Display will adhere to the shape of the input spectrum to capture the frequencies present in the Spill material. 

Click this button only when the undesired spill part of the signal is being played to learn the Spill signal. If necessary, the button can be held after clicking to include any further spill material that may occur after clicking. Just make sure the button is released before any of the desired Source signal is played, otherwise it will be picked up as part of the Spill signal.

 

Clear

Clears all learned Source and Spill data and resets them back to default (flat).

 

Spectrum Display

The Spectrum Display provides a visual for the Source, Spill, and input data and also allows you to manually adjust the learned Source and Spill curves. 

The green line shows the learned Source signal and the red line shows the learned Spill signal. These are both flat by default, but will update whenever new Source and Spill signals are learned. 

During playback, a spectral analysis of the input signal will be displayed behind the Source and Spill lines. Any parts of the input spectrum that are above the Spill line and below the Source line will be highlighted in green as this is the Source signal that triggers the gate to open. Any input signal outside of the Source and Spill lines will be treated as Spill and therefore will not trigger the gate.

  <- Source signal highlighted in green

Whenever the Learn Source or Learn Spill buttons are engaged, the corresponding lines will be automatically adjusted across the spectrum to match the input signal for as long as the button is held down. 

The Source and Spill lines each have 24 adjustable nodes at fixed frequencies across the spectrum. These nodes can be clicked and dragged vertically to manually set the Source/Spill shapes if necessary.

 

Threshold/Signal Meter

The Threshold slider is attached to the Signal Meter that displays the level of the Source signal (the part highlighted in green on the Spectrum Display). The Source signal refers to any input signal that is present above the Spill level and below the Source level as this is the signal that triggers the gate to open/close. The Threshold sets the level between this range in which the gate will open/close according to the signal level. If the signal level reaches or exceeds the Threshold, the gate will open and allow the signal to pass through unaffected. If the signal is below the Threshold, the gate will close and attenuate the signal by the amount set by the Depth control. 

The Signal Meter will only display a signal if some part of the input signal is present in the Source range (above the Spill line and below the Source line). The meter data will display green whenever the signal is at or above the threshold and red if it is below the threshold to reflect when the gate opens and closes.

 

Hold, Release & Depth

Hold: Sets the amount of milliseconds the gate will remain open after the signal has dropped below the Threshold. This essentially delays attenuation from occuring by a certain amount of time after the gate is triggered to close in order to allow the tail of the signal to pass through.

Release: Sets the amount of milliseconds it takes for the gain reduction to reach full attenuation (determined by the Depth) after the gate closes.

Depth: Sets the maximum amount of gain reduction that is applied when the gate is closed. 

Note that if the Depth is set to the minimum value of 0dB, no gain reduction will be applied and the gate will have no effect on the signal.

 

Reduction Meter

 Displays the level of gain reduction applied to the signal when the gate is closed.

 

Usage Example

In this example, say you have a snare drum track containing audible spill from other drums picked up by the snare microphone. You want to gate the snare so that all parts of the signal that don’t contain a snare hit are attenuated. The Spectral Gate can be used to achieve this quickly and effectively by setting it to learn the difference between the desired snare hit signal and the undesired spill signal.

While the snare track is playing, click the Learn Source button at the same time any snare hit occurs. If available, find a part of the track where the snare is the only drum present in the signal for best results. You only need to capture the initial transient (the loudest part) of the hit. In most cases, this can be accomplished by clicking and immediately releasing the button on time with the snare hit, but you can also hold the button down for the entire duration of the snare transient and tail and it will automatically pick up the loudest part of the hit. Just don’t keep the button held down long enough to pick up any spill that occurs after the snare hit. You will see that the green Source line on the Spectrum Display now outlines the shape of the input signal spectrum whenever a snare hit occurs. In some cases you may have to do this more than once to achieve an accurate measurement.

  Source line outlines the snare transient

Now the Source signal has been learned, but we also want to learn the Spill signal to achieve the best results. Click the Learn Spill button during a part of the snare track that contains the undesired spill that you want to gate out. This may include hi-hat, kick or tom hits that occur in between snare hits. You may hold down the Learn Spill button for the entire duration of the spill section(s) to make sure all elements of the Spill signal are captured, but of course you’ll want to be sure to release the button before the next snare hit occurs so that it doesn’t get recognized as part of the Spill signal. You will see that the red Spill line on the Spectrum Display now outlines the shape of the input signal spectrum whenever the designated Spill of the signal occurs. In some cases you may have to do this more than once to achieve an accurate measurement.

 Spill line outlines the spill signal

 

Tip: If you’re having trouble clicking the Learn Source or Learn Spill buttons at the right time, you can set your DAW to loop over the intended Source and Spill sections of the track to make them easier to capture. Alternatively, you can always manually adjust the Source/Spill nodes on the Spectrum Display by clicking and dragging them to match the input spectrum at the appropriate parts of the signal. 

 

Now that both the Source and Spill have been learned, the gate will be triggered to open only when there is signal present in the Source range (above the Spill line and Below the Source line). These parts of the input signal are highlighted in green on the Spectrum Display. The Signal Meter to the right of the Spectrum Display will show the level of the Source signal each time the snare is hit. Simply adjust the Threshold slider attached to the meter so that the gate opens on every snare hit, and now the gate should be properly triggered off of the snare and you can adjust the Hold, Release, and Depth controls to set the sound to your liking. 

  Gate triggered on snare hit 

 

Note: The Spectral Gate operates under the assumption that the Source signal is greater than the Spill signal in at least one part of the spectrum and will not work as intended if the Spill is greater than the Source throughout the entire spectrum.

 

Additional Features

At the top-right corner of the plugin window are the Momentary Bypass and Settings buttons.

Momentary Bypass

The Momentary Bypass button bypasses the plugin for as long as it's held. This is useful for auditioning A/B comparisons quickly. 

 

Settings

The Settings button reveals a pop-up menu where the window size can be adjusted. It also contains a link to the plugin manual and version info at the bottom.

 

Control Behaviors & Shortcuts

Various mouse & keyboard shortcuts can be used to perform certain actions on the following controls:

Sliders/Knobs

 

Labels

 

Combo Boxes (Drop-down menus)

 

Band Controls

 

Graph Rulers

 

System Requirements

Your system should meet one of the following OS version requirements in order to run Harrison plugins:

PC:

• Windows 11
• Windows 10*

Macintosh:

• macOS 26 Tahoe
• macOS 15 Sequoia
• macOS 14 Sonoma
• macOS 13 Ventura – 10.15 Catalina*

* NOTE: We do not actively test these older operating systems as they are no longer supported by their respective developers, but we currently know of no reasons the current versions of our plug-ins will not work on these systems. That said, your mileage may vary; if you are running an older OS version, we recommend you demo our product to verify that it is compatible with your system before purchasing. If you need access to older versions of our products, please check the SSL/Harrison Legacy Plugins Download list.

macOS Apple Silicon/ARM Support: This plug-in is provided as a universal binary for macOS and features native Apple Silicon support.

Note for Pro Tools users: Pro Tools 11 or higher is required on Mac, 10.3.5 or higher is required on Windows.

Additional requirements on Windows

Harrison plugins require the “Windows C++ Universal Runtime” to be installed on your computer.  Universal runtime is part of the system’s core libraries on Windows 10. On Windows versions Vista to 8.1,  it will be automatically installed via Windows Update. It is also possible to install the runtime manually, but that is outside the scope of this manual.

Note for Linux Users

If you’re experiencing issues with the plugin’s graphics or the GUI isn’t showing up correctly on Linux, make sure your system’s graphics driver supports the minimum required OpenGL version of 3.2 or higher. To check this, run glxinfo | grep Max in a terminal window and make sure that the value listed for the OpenGL core profile version string is at least 3.2 or greater.

If your core profile version meets this requirement but you are still experiencing graphics issues like the ones mentioned above, it is likely that your system is reporting an OpenGL version lower than 3.2 to ensure backwards compatibility with deprecated OpenGL functions. To work around this, you can force the system to report an OpenGL version of 3.2 or higher by setting this environment variable: MESA_GL_VERSION_OVERRIDE=3.2

You can use this as a prefix when opening your DAW from a terminal command like so:

MESA_GL_VERSION_OVERRIDE=3.2 {command_to_launch_program}

This will set the environment variable for that particular terminal session only, so it will be reset once the session is ended. If you don’t want to run this command every time you launch your DAW, you can set the environment variable in your profile script so that it automatically gets set every time you login.

 

Installation & Licensing

Licensing on macOS & Windows

This plugin is licensed through iLok on macOS and Windows. Visit iLok, Licensing and Activation for guidance on activating your Harrison plug-in. 

 

Licensing on Linux

This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit (http://www.openssl.org/)

In DEMO mode, after using the plugin for a certain amount of time, it will display a message:

This message will come up periodically unless a license is provided. You can purchase a license directly from Harrison’s web store or from an authorized plugin reseller. Once you’ve purchased a license, install it by entering your license key into the designated field on this screen. Continue to the next section for detailed instructions on how to obtain your license key. 

Obtaining your License Key

After you purchase a license, you will receive a license key that will look something like this:

{your  name}*AVA-BF*DC-138971-151520-1|gGLbnvCZJe386ULohzfQN6cIsoZ71n7c+AUg==|

This license key is required to install your license and activate the full version of the plugin. The way to obtain your license key varies depending on where you purchased the license from.

If you purchased the license from Harrison’s web store, you will receive an email with a link to download a text file containing your license key. If you purchased the license from a reseller, you will receive an email containing the license key text.

 

Licensing your Plugin

When prompted by the plugin, copy and paste your license key into the designated text input field. This will automatically install your license and register it with the plugin.

Once installed, Harrison’s license files are simple text (.txt) files which are stored in the user’s HOME folder. The HOME folder is the folder that contains your Desktop, Downloads and other folders. The location of your HOME folder is different for each operating system:

• Linux: /home/{your username}

You may keep a copy of this file for your own use. The license is a per-user license and you may install the license file on all of your computers. To install the file on a new computer, simply save the file to a USB key or other transferable disk; then transfer the license file to the new computer’s HOME folder. The license file has your name encrypted in it, so you should not share it with other people. Your name will appear on the top of the plugin’s control panel to indicate that it is licensed to you.

The plugin will automatically detect your license key as long as the license file is stored in the HOME folder of the computer you are using. After transferring the license file to a new computer, it may be necessary to close and re-open your DAW in order for the plugin to detect the license.

If you don’t want to keep your license in your HOME folder for whatever reason, you may also store it in the following alternative location:  ~/.config/harrisonconsoles

 

Finding the plugin in your DAW 

DAW operations vary tremendously. Generally speaking, to use the plugin you must follow these steps:

1. Install the plugins, using the provided plugin installer application.
2. Follow your DAW’s instructions to “scan” for new plugins.

Please refer to your DAW manual to see which plugin formats (AAX, AU, VST, or VST3) are supported by your workstation.

Most plugin formats require that plugins are installed to a specific location on the system. In these cases, the installer will place the plugins in the default locations.

For VST format, on Windows, it is normally expected that the user defines the location of VST plugins, and tells the workstation where to find the plugins. The default location for VST plugins is C:\Program Files\Steinberg\VST.  The plugin installer will save the VST (.dll) files to that location if a custom VST path is not provided by the OS.  If you are having trouble, you should verify that the path is included in your DAW VST scan paths.

 

Thank you for purchasing this Harrison plugin!

Harrison has been making products for the audio engineering industry since 1975. We continue to make these products, with intense dedication, from our Nashville, Tennessee factory.  

As the audio industry has changed through the decades, Harrison has too. Originally launched to provide mixing consoles for music recording studios, the Harrison brand has extended to provide products for live broadcast, live sound, theater installations, post-production, film dubbing stages, and bedroom studios. We’ve lived through the launch of the commercial music industry, the maturation of analog, the digital revolution, the establishment of the internet, and now the acceptance of computers as the de-facto platform for the audio industry. In our pursuit of audio excellence, we’ve developed our own analog circuits, digital I/O solutions, digital DSP engines, control surfaces, audio workstations, and nearly every aspect of pro-audio technology.

“If you asked a hundred engineers, mixers and producers to define the “perfect console” you would probably get a hundred answers. The answers, however, would all contain the same salient points.”
“The “perfect console” would have totally transparent sound, capturing the true musical quality of all performances. It would have unlimited features, facilities, and functions. It would perform all required tasks with a minimum of operator effort. It would be totally reliable and require no preventive or corrective maintenance…
You can spend the rest of your life looking for the “perfect console”. You’ll never find it. You will find, however, that we have what you need.”- quote attributed to Dave Harrison;  Harrison MR20 brochure; circa 1982

True-er words were never spoken; indeed every year there are many products and technologies that seem tantalizingly necessary for audio excellence. Our lasting experience has proven that simple, straightforward, well-engineered, and great-sounding tools are the only necessity.

These plugins represent the pinnacle of Harrison’s engineering practices for digital audio sound & workflow. We sincerely hope that you enjoy using these tools as much as we enjoyed creating them. Your continued support is greatly appreciated!